13-02-2011, 10:52 PM
Alex Mini:
After several false started with a faulty ESC & Dead stick landing then faulty motor and dead stick landing I decided to bite the bullet and put a decent motor into my hotliner that hasn't seen a real flight in the almost 12months since I got it.
I opted for a Neu 1509g 1.5D with a 6.7:1 Gearbox & Castle Creations 125amp ESC.
We spent last Sunday getting the sizeable motor installed into the airframe.
The plan was to test fly yesterday as I had to do church on Sunday, bad weather messed those plans up so eager to fly the plane I ran down to the field first chance I had on Sunday. I met everyone else walking out.
The first flight went well, I never went over half throttle and noted that the plane was a tad on the tail heavy side which meant it didn't retain energy at all, I got her all trimmed out and landed the thing at my feet (A far cry from the 50km final leg the ol' siren needed!)
I chucked in a fresh battery and gave her a toss, I thought this is it! Punched the throttle and sent the Alex skywards at an extreme rate, The performance was astounding, I was grinning ear to ear as I looped over the top and brought her down for a howling low pass. I only managed half a circuit before the energy washed off so I punched it again for a mach run down the field... Much faster than ol' Siren and the best part at the back of my mind was that according to the calculations, I was only barely pushing the motor. I'm running 13x8 for over 1400watts but the optimal setup is in the range of a 14x18!!!! Yes thats EIGHTEEN! (they don't make em that fat but you can get centerpieces to compensate)
Any how, I performed a few more boost/cruises then decided to set up for an approach. This is when disaster struck:
I was setting up as per usual over the far western end of the field and was getting a little low so I opened the throttle, to my surprise there was no response! I didn't panic initially as I'd had issues like this with hot setups before so I instinctively closed and reopened the throttle to try for a second & third kick, Getting quite low now I started having to pull back to keep the glider visible above the tree's, In a split second I thought this is it, she's going in. I lost sight for a micro second and then the motor kicked to life and she re-appeared for a moment! Unfortunatley at this stage I was in an advanced stall, she promptly dropped and wing and literally turned into a rifle a shot, accelerating rapidly in a horizontal flight path while rolling FAST, I couldn't catch it and killed the power and lost sight again...
I stood there dumbfounded. My new baby, my pride and joy gone after sooo much time & effort, not just mine but Darren's as well... I kicked the ground, HARD! Picked up my gear (Had walked in with my Heli as well as my tx case and started the walk of misery. It literally took me 20 minutes to get to the crash site as the ground was soo wet and It landed soo far away!
When I got there I found this:
That's a good 15-20cm of fuse submerged there! The motor, battery & esc were underwater. It was actually still on the air! I gave the elevator a wave as I walked up just to make sure it wasn't RX failure. As I got closer, the esc/motor were actualy beeping away! sounds quite weird underwater!
The wing was a few feet away, Unscathed:
It turns out the wing saddle bolts were only biting into hardwood and so the wing probably came off quite easy on impact.
There are no more photo's cos I was absolutely gutted at this point, although the fuse and wing were clearly intact/undamaged, the amount of mud/water that came out with the fuse when I extracted it was terrible.
It took me another 30 mins to juggle the muddy wreck, tx case & heli back to the car. Once there I went around to Darren's to perform the post mortem, as per usual he was more confident about fixing than me! We literally hosed the mud off and bathed everything in clean water before blowing it with the hair dryer. The motor looked fine at first but we had trouble getting it to turn smoothly so after tearing it down and rebuilding a few times we discovered some loose magnetic shards which could have contributed to the motor not starting. These shards were NOT from the motor itself, all the magnets were intact, they were possibly leftovers from when this motor was refurbished at Neu after Darren blew it up by feeding it 14v too many! Unfortunatley it seems the ESC has been damaged by the extended bath. The BEC still functions and it will spin the motor, we just can't get it to draw more than 30amps before it starts giving up. We're going to let it dry some more and try through the week but I will be probably looking at buying a replacement ESC (Painful, they ain't cheap!)
Maybe fourth time will be the charm for this bird!
After several false started with a faulty ESC & Dead stick landing then faulty motor and dead stick landing I decided to bite the bullet and put a decent motor into my hotliner that hasn't seen a real flight in the almost 12months since I got it.
I opted for a Neu 1509g 1.5D with a 6.7:1 Gearbox & Castle Creations 125amp ESC.
We spent last Sunday getting the sizeable motor installed into the airframe.
The plan was to test fly yesterday as I had to do church on Sunday, bad weather messed those plans up so eager to fly the plane I ran down to the field first chance I had on Sunday. I met everyone else walking out.
The first flight went well, I never went over half throttle and noted that the plane was a tad on the tail heavy side which meant it didn't retain energy at all, I got her all trimmed out and landed the thing at my feet (A far cry from the 50km final leg the ol' siren needed!)
I chucked in a fresh battery and gave her a toss, I thought this is it! Punched the throttle and sent the Alex skywards at an extreme rate, The performance was astounding, I was grinning ear to ear as I looped over the top and brought her down for a howling low pass. I only managed half a circuit before the energy washed off so I punched it again for a mach run down the field... Much faster than ol' Siren and the best part at the back of my mind was that according to the calculations, I was only barely pushing the motor. I'm running 13x8 for over 1400watts but the optimal setup is in the range of a 14x18!!!! Yes thats EIGHTEEN! (they don't make em that fat but you can get centerpieces to compensate)
Any how, I performed a few more boost/cruises then decided to set up for an approach. This is when disaster struck:
I was setting up as per usual over the far western end of the field and was getting a little low so I opened the throttle, to my surprise there was no response! I didn't panic initially as I'd had issues like this with hot setups before so I instinctively closed and reopened the throttle to try for a second & third kick, Getting quite low now I started having to pull back to keep the glider visible above the tree's, In a split second I thought this is it, she's going in. I lost sight for a micro second and then the motor kicked to life and she re-appeared for a moment! Unfortunatley at this stage I was in an advanced stall, she promptly dropped and wing and literally turned into a rifle a shot, accelerating rapidly in a horizontal flight path while rolling FAST, I couldn't catch it and killed the power and lost sight again...
I stood there dumbfounded. My new baby, my pride and joy gone after sooo much time & effort, not just mine but Darren's as well... I kicked the ground, HARD! Picked up my gear (Had walked in with my Heli as well as my tx case and started the walk of misery. It literally took me 20 minutes to get to the crash site as the ground was soo wet and It landed soo far away!
When I got there I found this:
That's a good 15-20cm of fuse submerged there! The motor, battery & esc were underwater. It was actually still on the air! I gave the elevator a wave as I walked up just to make sure it wasn't RX failure. As I got closer, the esc/motor were actualy beeping away! sounds quite weird underwater!
The wing was a few feet away, Unscathed:
It turns out the wing saddle bolts were only biting into hardwood and so the wing probably came off quite easy on impact.
There are no more photo's cos I was absolutely gutted at this point, although the fuse and wing were clearly intact/undamaged, the amount of mud/water that came out with the fuse when I extracted it was terrible.
It took me another 30 mins to juggle the muddy wreck, tx case & heli back to the car. Once there I went around to Darren's to perform the post mortem, as per usual he was more confident about fixing than me! We literally hosed the mud off and bathed everything in clean water before blowing it with the hair dryer. The motor looked fine at first but we had trouble getting it to turn smoothly so after tearing it down and rebuilding a few times we discovered some loose magnetic shards which could have contributed to the motor not starting. These shards were NOT from the motor itself, all the magnets were intact, they were possibly leftovers from when this motor was refurbished at Neu after Darren blew it up by feeding it 14v too many! Unfortunatley it seems the ESC has been damaged by the extended bath. The BEC still functions and it will spin the motor, we just can't get it to draw more than 30amps before it starts giving up. We're going to let it dry some more and try through the week but I will be probably looking at buying a replacement ESC (Painful, they ain't cheap!)
Maybe fourth time will be the charm for this bird!